[layoutng] Support computing min-content and max-content

third_party/WebKit/Source/core/layout/ng/ng_box.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/layout/ng/ng_box.h"
 
 #include "core/layout/LayoutBlockFlow.h"
 #include "core/layout/ng/layout_ng_block_flow.h"
 #include "core/layout/ng/ng_block_layout_algorithm.h"
+#include "core/layout/ng/ng_constraint_space_builder.h"
 #include "core/layout/ng/ng_constraint_space.h"
 #include "core/layout/ng/ng_direction.h"
 #include "core/layout/ng/ng_fragment.h"
 #include "core/layout/ng/ng_fragment_builder.h"
 #include "core/layout/ng/ng_length_utils.h"
 #include "core/layout/ng/ng_writing_mode.h"
 
 namespace blink {
 
 NGBox::NGBox(LayoutObject* layout_object)
     : layout_box_(toLayoutBox(layout_object)) {
   DCHECK(layout_box_);
 }
 
 NGBox::NGBox(ComputedStyle* style) : layout_box_(nullptr), style_(style) {
   DCHECK(style_);
 }
 
 bool NGBox::Layout(const NGConstraintSpace* constraint_space,
                    NGFragment** out) {
+  DCHECK(!minmax_algorithm_)
+      << "Can't interleave Layout and ComputeMinAndMaxContentSizes";
   if (layout_box_ && layout_box_->isOutOfFlowPositioned())
     layout_box_->containingBlock()->insertPositionedObject(layout_box_);
   // We can either use the new layout code to do the layout and then copy the
   // resulting size to the LayoutObject, or use the old layout code and
   // synthesize a fragment.
   if (CanUseNewLayout()) {
     // Change the coordinate system of the constraint space.
     NGConstraintSpace* child_constraint_space = new NGConstraintSpace(
         FromPlatformWritingMode(Style()->getWritingMode()),
         FromPlatformDirection(Style()->direction()),
         constraint_space->MutablePhysicalSpace());
 
-    if (!algorithm_)
-      algorithm_ = new NGBlockLayoutAlgorithm(Style(), FirstChild(),
-                                              child_constraint_space);
+    if (!layout_algorithm_)
+      layout_algorithm_ = new NGBlockLayoutAlgorithm(Style(), FirstChild(),
+                                                     child_constraint_space);
 
     NGPhysicalFragment* fragment = nullptr;
-    if (!algorithm_->Layout(&fragment))
+    if (!layout_algorithm_->Layout(&fragment))
       return false;
     fragment_ = fragment;
 
     if (layout_box_) {
       CopyFragmentDataToLayoutBox(*constraint_space);
     }
   } else {
     DCHECK(layout_box_);
     fragment_ = RunOldLayout(*constraint_space);
   }
   *out = new NGFragment(constraint_space->WritingMode(),
                         FromPlatformDirection(Style()->direction()),
                         fragment_.get());
   // Reset algorithm for future use
-  algorithm_ = nullptr;
+  layout_algorithm_ = nullptr;
   return true;
 }
 
+bool NGBox::ComputeMinAndMaxContentSizes(MinAndMaxContentSizes* sizes) {
+  DCHECK(!layout_algorithm_)
+      << "Can't interleave Layout and ComputeMinAndMaxContentSizes";
+  if (!minmax_algorithm_) {
+    NGConstraintSpaceBuilder builder(
+        FromPlatformWritingMode(Style()->getWritingMode()));
+
+    builder.SetContainerSize(NGLogicalSize(LayoutUnit(), LayoutUnit()));
+    // TODO(layoutng): Use builder.ToConstraintSpace.ToLogicalConstraintSpace
+    // once
+    // that's available.
+    NGConstraintSpace* constraint_space = new NGConstraintSpace(
+        FromPlatformWritingMode(Style()->getWritingMode()),
+        FromPlatformDirection(Style()->direction()),
+        builder.ToConstraintSpace());
+
+    minmax_algorithm_ =
+        new NGBlockLayoutAlgorithm(Style(), FirstChild(), constraint_space);
+  }
+  // TODO(cbiesinger): For orthogonal children, we need to always synthesize.
+  NGLayoutAlgorithm::MinAndMaxState state =
+      minmax_algorithm_->ComputeMinAndMaxContentSizes(sizes);
+  if (state == NGLayoutAlgorithm::Success)
+    return true;
+  if (state == NGLayoutAlgorithm::Pending)
+    return false;
+  DCHECK_EQ(state, NGLayoutAlgorithm::NotImplemented);
+
+  // TODO(cbiesinger): Replace the loops below with a state machine like in
+  // Layout.
+
+  // Have to synthesize this value.
+  NGPhysicalFragment* physical_fragment;
+  while (!minmax_algorithm_->Layout(&physical_fragment))
+    continue;
+  NGFragment* fragment = new NGFragment(
+      FromPlatformWritingMode(Style()->getWritingMode()),
+      FromPlatformDirection(Style()->direction()), physical_fragment);
+
+  sizes->min_content = fragment->InlineOverflow();
+
+  // Now, redo with infinite space for max_content
+  NGConstraintSpaceBuilder builder(
+      FromPlatformWritingMode(Style()->getWritingMode()));
+  builder.SetContainerSize(NGLogicalSize(LayoutUnit::max(), LayoutUnit()));
+  NGConstraintSpace* constraint_space = new NGConstraintSpace(
+      FromPlatformWritingMode(Style()->getWritingMode()),
+      FromPlatformDirection(Style()->direction()), builder.ToConstraintSpace());
+
+  minmax_algorithm_ =
+      new NGBlockLayoutAlgorithm(Style(), FirstChild(), constraint_space);
+  while (!minmax_algorithm_->Layout(&physical_fragment))
+    continue;
+
+  fragment = new NGFragment(FromPlatformWritingMode(Style()->getWritingMode()),
+                            FromPlatformDirection(Style()->direction()),
+                            physical_fragment);
+  sizes->max_content = fragment->InlineOverflow();
+  minmax_algorithm_ = nullptr;
+  return true;
+}
+
 const ComputedStyle* NGBox::Style() const {
   if (style_)
     return style_.get();
   DCHECK(layout_box_);
   return layout_box_->style();
 }
 
 NGBox* NGBox::NextSibling() {
   if (!next_sibling_) {
     LayoutObject* next_sibling =
@@ skipping 14 matching lines @@
 }
 
 void NGBox::SetNextSibling(NGBox* sibling) {
   next_sibling_ = sibling;
 }
 
 void NGBox::SetFirstChild(NGBox* child) {
   first_child_ = child;
 }
 
+DEFINE_TRACE(NGBox) {
+  visitor->trace(layout_algorithm_);
+  visitor->trace(minmax_algorithm_);
+  visitor->trace(fragment_);
+  visitor->trace(next_sibling_);
+  visitor->trace(first_child_);
+}
+
 void NGBox::PositionUpdated() {
   if (!layout_box_)
     return;
   DCHECK(layout_box_->parent()) << "Should be called on children only.";
 
   layout_box_->setX(fragment_->LeftOffset());
   layout_box_->setY(fragment_->TopOffset());
 
   if (layout_box_->isFloating() && layout_box_->parent()->isLayoutBlockFlow()) {
     FloatingObject* floating_object = toLayoutBlockFlow(layout_box_->parent())
@@ skipping 69 matching lines @@
       .SetBlockSize(layout_box_->logicalHeight())
       .SetDirection(FromPlatformDirection(layout_box_->styleRef().direction()))
       .SetWritingMode(
           FromPlatformWritingMode(layout_box_->styleRef().getWritingMode()))
       .SetInlineOverflow(overflow.width())
       .SetBlockOverflow(overflow.height());
   return builder.ToFragment();
 }
 
 }  // namespace blink